Telescoping core drill



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March 22; 1960 Filed May 20, 1957 paw an F. 1.. LE Bus, SR 2,929,612

TELESCOPING some: DRILL 5 Sheets-Sheet 1 Fl l-A g INVENTOR. A. Le Bus 5/:

Q. ATTORNEY 1 7 March 1Z2, 1960 F. L. LE BUS, SR 2,929,612

TELESCOPING CORE DRILL Filed May 20, 1957 5 Sheets-Sheet 2 INV ENT OR.

E Z. [e 505 5/:

March 22, 1960 F. LE Bus, SR

TELESCOPING CORE DRILL 5 Sheets-Sheet 3 Filed May 20, 1957 INVENTOR. F L. LeBus 5/:

BY ATTORNEYQ March 22, 1960 F. L. LE BUS, SR 2,929,612

TELESCOPING CORE DRILL Filed Bay 20, 1957 5 Sheets-Sheet 4 l 90;"I I

: I l I i in l I i F ./0 9 54 gaa-A FZZyQ-A MENTOR.

A Lie Bus 5/:

W ATTORNEY March 22, 1960 F. 1.. LE BUS, SR

TELESCOPING CORE DRILL 5 Sheets-Sheet 5 Filed May 20, 1957 INVENTOR. EL Le Bus 5/:

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A m z TELESCOPING CGRE DRILL Franklin L. Le Bus, Sn, Longview, Tex., assignor to Le Bus Royalty Company, Longview, Tex., a partnership Application May 20, 1957, Serial N0. 660,206 7 8 Claims. (Cl. 255-72) This invention relates to an improved core drill unit for oil well bores, and more particularly, but not by way of limitation, to a core barrel unit particularly designed and constructed to permit the insertion of additional pipe sections in the drill string without raising the core drill and core barrel from the bottom of the hole.

In the drilling of oil wells, and particularly wildcat wells and the like for the purpose of finding new sources of oil, it is frequently desirable to core drill the well bore in order to obtain the most reliable information possible regarding the subsurface formation. As is well known, it is particularly desirable to obtain or recover as long a core sample as possible for an efiicient analysis of the subsurface formation. In order to do this, it is usually necessary to stop the coring operation at intervals for inserting additional pipe sections in the drill string. When the drill string is lifted in the well bore for the addition of the pipe section, the core drill and core barrel are normally raised therewith. As a result the core sample is broken, leaving a core stub extending upwardly from the bottom of the well bore. It is well known that most oil producing formations are usually deformed in an incline or anticline relation, consequently, the broken core stub usually results in a cone or wedge shape, and on the return of the drill string and core bit to the bottom of the well, this wedge shape core stub may cause jamusing of the core sample already contained in the core barrel and making it impossible to continue the coring operation. Thus, not only does the drill string and bit have to be pulled from the well, but portions of the core sample material are often ruined, resulting in the loss of valuable core information. Furthermore, when the core drill is raised from the bottom of the well bore, a trap is formed therein for the accumulation of broken rock bit teeth, chert and other types of hard pebbles. When the core drill is lowered to continue the drilling operation, these hard particles usually roll around under the core drill and often seriously damage the cutting portions thereof. In this instance, the core drill must be pulled from the well for replacement. Not only is the core drill itself expensive to replace, but the time lost during the pulling operation greatly adds to the cost of the drilling operation, particularly in deep well bores.

in addition, the inner core barrel housing is usually connected with the outer tubular housing of the drill string for a simultaneous rotation therewith during the coring operation. Thus, the inner core barrel, wherein the c ore'sample is accumulated, rotates continuously during the coring operation, causing an additional wear and distortion on the core sample therein.

nite sates Patent of the well bore.

2 unit provided with complementary spline members for permitting the insertion of additional pipe sections in the drill string without raising the core drill from the bottom Not only is the life of the bit thus greatly increased, but it is also possible to recover a core sample of substantially any desired length without. the danger or" jamming the core sample within the core barrel. Furthermore, a free wheeling connection is provided between the outer core barrel and inner core barrel whereby the outer co're barrel may be rotated independently of the inner barrel during the coring operation for facilitating the recovery of the core sample within the inner barrel.

It is an important object of this invention to provide a novel core drill unit so designed and constructed to permit the insertion of additional pipe sections in the drill string without raising the core bit from the bottom of the well bore.

It. is another object of this invention to provide a novel core drill unit so designed and constructed to permit the recovery of a core sample of substantially greater length and substantially eliminating the possibility of jamming the core sample within the barrel during the coring operation.

Another object "of this invention is to provide a free wheeling core drill unit wherein the outer core barrel may be rotated independently of the inner core barrel for facilitating the core drilling operation.

Still another object of this invention is to provide a novel core drill unit for substantially decreasing the time and cost of the core drilling operation.

And still another object of this invention is to provide a core drill unit which is simple and eflicient in operation and economical and durable in construction.

Other objects and advantages of the invention will be evident from the following detailed description, read in conjunction with the accompanying drawings, which illustrate my invention.

in the drawings:

Figure 1 is a broken vertical sectional elevational view of the upper portion of the novel core drill unit.

Figure 1A is a view similar to Fig. 1 of the lower portion of the core drill unit.

Figure 2 is a broken elevational view of the novel core drill unit with portions thereof in dotted lines for clarity in depicting the male spline member in an operation position for either drilling or coming directly of the spline tracks in a vertical upward or downward direction within the well bore.

Figure 3 is a view similar to Fig. 2 depicting the'male spline member locked in the J-slot for lowering or raising the entire unit in the well bore.

Figure 4 is a sectional view taken on line 44 of Fig; l.

Figure 5 is a sectional view taken on line 55 of Fig. '1

Figure 61s a sectional view taken on line 6-6 of Fig.3.

Figure 7 is a sectional view taken on line 7-7 of Fig. 1A.

Figure 8 is a sectional view taken on line 8-8 of Fig. 1A.

Figure 9 is a broken elevational view partly in section of the-upper portion of the 'entireunit in a locked position for lowering or raising the unit in the well'bore.

Figure 9A is a view similar to Fig. 9 of the lower The present invention contemplates a novel core drill '55 portion of thecoredrillunit.

Figure is a view similar to Fig. 9 depicting the upper portion of the complete unit in a drilling position.

Figure 10A is a view similar to Fig. 9A of the lower portion of the core drill unit in a drilling position.

Figure 11 is a view similar to Fig. 9 of the upper portion of the complete drill unit with the outer jacket in a raised position for the insertion of an additional pipe section in the drill string.

Figure 11A is a view similar to Fig. 9A of the lower portion of the complete unit in a raised position.

Figure 12 is a view similar to Fig.9 of the upper portion of the drill unit with the outer jacket approaching its upper limit with respect to the inner jacket.

Figure 12A is a view similar to Fig. 9A of the lower i portion of the complete unit with the outer jacket apf proaching its upper limit.

'Referring to the drawings in detail, and particularly Figs. 1 and 1A, reference character 10 indicates in general the novel core drill unit comprising an'upper pin or sub memberj 12 threaded at 14 for connection with a drill string or drill collar (not shown). The 'sub' member 12 extends downwardly into threaded, connection at 16 with an outer jacket or sleeve member 18, which in turn extends downwardly into threaded connection at 20 with a lower outer jacket member 22. The inner periphery of the jacket member 22 is provided with a plurality of circumferentially spaced inwardly projecting lug or spline members 24, preferably two diametrically opposed members adapted to cooperate with an inner or female spline body generally indicated at 26. There is no connection between the outer jackets 18, 22 and the inner spline body 26 other than the spline connections, as will be hereinafter set forth.

The inner spline body 26 comprises a tubular member 28 of a smaller outer diameter than the inner diameter of the outer jackets 18,22 whereby the outer jacket may be telescopically disposed thereover. A plurality of substantially J-shaped grooves 30, preferably two diametrically opposed grooves are circumferentially spaced on the outer periphery of the member 28. Each of the J-shaped grooves 30 are provided with one vertical groove portion 32 (Fig. 2) having the upper end thereof open for re- 7 ceiving the male spline members 24. An uninterrupted vertical shoulder 33 istp rovided adjacent each of the grooves 32. A second vertical groove portion 34 is provided in the J-slot 30 having the upper end thereof closed by a substantially horizontal shoulder 36 for a purpose as will be hereinafter set forth A helical of spiral shoulder 38 extends from the vertical-slot 32 to the slot 34 for facilitating the movement of the male lugs 24 from one of the vertical slots 32 to the slot 34, and vice versa, as will be hereinafter set forth. An upper spiral shoulder 40 is provided in the proximity of the top of the sleeve 28 and is in communication with the open end of the vertical groove 32 for facilitating the disposition of the lug members 24 within'th'e groove 32 upon a downward movement of the outer jackets 18,

22 with respect to the inner spline body 26.

' naemia t- The inner spline body 26 below the lower spiral shoulder 38 is enlarged at 42 .to a diameter only slightly less'thanthe inner diameter of the outer jackets 18, 22. The enlarged portion 42 is provided with a plurality of longitudinally spaced annular or torodial sealing ring 7 members 44 adapted for seating against the inner periphery of the outer jackets 18, 22 for providing a sealing contact thereagainst. An outwardly extending circumferential shoulder 46 is provided on' the inner spline body 26 spaced below the packing or sealing ring members 44 forreceiving the lower end 48 of the lower outer jacket member 22, as clearly shown in Figs. 1A and 10A. It will be apparent that the shoulder 46 limits the downward movement of the outer jackets 18,

' 22 with respect to the inner spline body 26. The outer diameter of the inner splinesleeve or body 26 which extends downwardly from the shoulder 46 is substantially as is well known in the industry.

the same as the outer diameter of the outer jackets 18, 22, and extends downwardly into threaded connection at 50 with a connecting sleeve member 52. A suitable core drill or hit 56 is threaded at 54 to the lower end of sleeve 52.

Ah inner tubular housing member 58 (Figs. 2 and 6) is disposed within the inner or female spline body 26 and extends longitudinally therethrough. A plurality of circumferentially spaced longitudinal spline members 60 (Figs. 6 and 7) are provided on the outer periphery of the housing 58. A longitudinal passageway 62 is provided between each of the spline members 60, thereby forming a fluid passageway between the inner housing 58 and the female spline body 26. Only one of the passageways 62 is shown in dotted lines in Fig. 1A for purposes of clarity. 7 t V a The inner housing 58 extends downwardly through the spline body 26 into threaded connection at '64 to a-lower sub member 66 which is in turn threadedly connected at 68 to a second sub member or hearing sleeve member "70 (Fig. 1A). The sleeve member 70 extends there bearing sleeve member 70 is provided with an outwardly extending circumferential shoulder 78 (Figs. 1 and 8) in alignment with a plurality of inwardly extending circnmferentially spaced shoulders or lug members 80 provided on the inner periphery of the lowerend of the spline body 26. The cooperating shoulder 78 and lugs 80 receive and support a suitable circular split bearing member 82 to provide a bearing connection between the inner housing and the female spline body, thereby permitting a free wheeling of the inner spline body 26 and outer jacket 18, 22 with respect to the inner housing 58 and the collars connected therewith. An outwardly extending circumferential shoulder 84 is provided at the lower end of the sleeve or sub member 64, and is in alignment with a plurality of circumferentially spaced inwardly extending lugs 86 provided on the inner periphery of the spline body 26 and spaced upwardly from and complementary to the first lug members '80. The shoulder 84' and lug members 86 are disposed adjacent the upper surface of the bearing'member 82 and cooperate to retain the bearing 82in position between the inner housing and female spline body 26. as clearly shown in Fig. 1A. V

The inner housing member 58 extends upwardly from the spline body 26 and'into threaded connection at 88 (Fig. 1) to an upper sleeve 90.= The sleeve 90 and inner housing 58, along with the lower'sub members connected therebelow, form an inner core barrel housing for receiving and retaining a core sample (not shown) therein, It will be apparent in Figs. 1 and 10 that the inner core barrel housing extends upwardly within the outer jacket substantially the entire length thereof to provide for recovery of core samples of an extended length. The upper sleeve 90 is threadedly connected at the upper end 92 to an upper sub member 94which in turn is threadedly connected at'96 to a suitable valve cage member 98. A suitable valve seat is provided at the uppermost end of the sub member 94 for receiving a check valve ball member 102, for a purposeas will be hereinafter set forth.

A circumferential shoulder 104 is provided on the upper sub member 94 for supporting a suitable annular or circular bearing member 106. The bearing 106 is retained in position on the shoulder 104 by-means'ofa suitable bushingmember 108 which is in turn retained in position by the downwardly pressure of the valve cage member 98 bearing thereagainst. A plurality of circum- .ferentially spaced longitudinal bores 110 (Figs. 1 and 4) are provided in the bushing member 108 and into sleeve member's.

ray for fluid cireiilatio'n around the inner housing and The bushing member 108 cooperates with the bearing member 1:3-5 to provide f'a free wheeling action between the sub member 94 and the Outer jackets 18, 22. The sub member 94 is in connection with the inner core barrel housing, and therefore, the upper bean ing member 166 facilitates the free wheeling action provided by the lower bearing member 82 between the inner housing and outer spline body, as hereinbefore set forth.

Operation When it is desired to lower the core bit apparatus 56 into a well bore for obtaining a core sample of the subsurface formation, the jackets 18, 22 forming an outer housing 23 is telescoped downwardly over the spline body 26 at the well surface. As the male lug members 24 move downwardly over the spline body 26, the spiral shoulders 40 of the spline body automatically direct the lugs 24 into the open end of the vertical slots 32 without any manual rotation of the outer jacket. When the outer jacket 18, 22 has been lowered over the spline body 26 a sufiicient distance to position the lugs 24 at the lowermost end of the vertical slot 32, as shown in Figs. 1A and A, the outlet jackets 18, 22 is raised slightly and simultaneously rotated in a left hand or counterclockwise direction. The spiral shoulders 38 will guide the lug members into the second vertical groove 34, and a further raising of the outer jacket 18, 22 will move the lugs 24 into a position adjacent the horizontal shoulder 36 of the J-slots 30 as shown in Figs. 3 and 9A. In this position, the spline body will hang on the outer jacket members, whereupon the entire unit 10 may be lowered into the well bore in a locked position. I

When the unit is lowered to the bottom of the well bore, and it is desired to begin the coring operation, the outer jacket unit 23 is preferably lowered over the spline body and the lug members 24 are moved from the slot 34 into the slot 32 by the spiral shoulder 38. A right hand or clockwise rotation of the outer jacket 23 will move the lugs 24 into contact with the uninterrupted vertical shoulder 33, whereby the rotation of the outer jacket 18, 22 will be transmitted to the female spline body 26. It will be apparent from Figs. 1A and 10A that the lowermost position of the outer jacket 23 with respect to the female spline body 26 positions the lower end 48 of the outer jacket adjacent the circumferential shoulder 46, but there is no connection therebetween whatsoever. The rotation of the outer jacket is transmitted to the spline body through the contact between the lugs 24 and shoulder 33, and the rotation is simultaneously transmitted to the core bit 56 by means of the threaded connections on the sub member 52. However,

the inner core barrel 58 and the sleeve members carried thereby are connected to the spline body 26 only through the bearing members 82 and 106, and therefore, the rotation of the spline body is not transmitted to the inner core barrel. Thus, the spline body and outer jacket may free wheel, or rotate independently of the inner core barrel 53 during the coring operation for the recovery of the core sample.

When it is desired to insert an additional pipe section in the drill string (not shown), the outer jacket 23 is raised with respect to the female spline body 26. The lugs 24 move directly upward in the vertical slot 32 as shown in Fig. 2 and out the open end thereof as shown in Figs. 11 and 12, thereby permitting a raising of the outer jacket without movement of the spline body 26. Thus, the core bit 56 and core barrel 58 are not lifted from the bottom of the well bore at anytime during the insertion of the extra pipe section. When the outer jacket has been raised sufliciently to permit the insertion of the additional pipe section, the pipe section may be added to the drill string at the surface of the well, and the outer jacket 23 may again be lowered over the spline body 26 as hereinbefore set forth. In the lowering opera- 'tion, the spiral shoulders at; will automatically move the downwardly moving lugs 24 into the open end of the vertical slots 32, and the outer jacket may be rotated in a clockwise or right hand direction for continuing the coring operation. At no time during the insertion of the pipe section is the core bit 56 or inner core barrel disturbed in the well bore, thereby precluding the breaking of the core sample, or the danger of trapping hard pebbles beneath the core drill.

Figure 12 depicts the lug members 24 approaching their upper limit with respect to the inner core barrel housing 58-90 and the valve cage 98. The notches 112 provided in the bushing member 108 function as a clutch member for receiving the lugs 24 to limit the upward movement thereof and prevent a complete disengagement of the outer jacket 23 and the spline body 26.

Fluid circulating downwardly through the drill string during the drilling operation flows downwardly within the outer jacket member 18 and around the valve cage 98. The valve ball member 102 seats by gravity on the valve seat to preclude the passage of the fluid downwardly into the inner core barrel. However, any fluid contained or trapped within the inner core barrel is forced upwardly through the inner core barrel by the core sample (not shown) as the sample is collected and rises therein. The upward force of the sample collecting within the core barrel will move the ball 102 upwardly and oil the seat 100 to release the fluid pressure therefrom. The fluid circulating through the drill string will move downwardly through the bores provided in the bushing 1% and through the annular space 114 between the spline body 26 and the outer jacket 18, 22. The seal ring members 44 seal against the inner periphery of the outer jacket and preclude any further downward passage of the fluid therebetween. However, the fluid moves downwardly between the spline body 26 and the inner housing 58 through the passageways 62 provided on the outer periphery of the inner housing 58 and is discharged into the annular space H6 between the inner core barrel and the lower portion of the spline body 26, hence downwardly to and around the core bit 56 and discharge outlet for facilitating the coring operation.

When it is desired to raise the entire tool 10, including the outer jacket and the spline body 26 with the core bit 56 connected thereto, the outer jacket 23 may be raised slightly and simultaneously rotated in a counterclockwise or left hand direction for moving the lugs 24 into the vertical groove 34 and adjacent the horizontal shoulder 36 (Figs. 1A and 9A). In this position, the spline body 26 and outer jacket unit 23 are locked together, and an upward movement or raising of the outer jacket will function to elevate the entire tool 10 from the well bore. it will be apparent that the spline body 26 may be simultaneously rotated with the outer jacket 23 in the locked position by the contact of the lugs 24 with the side walls of the vertical groove 34, if desired, for facilitating either the drilling or removal operation.

From the foregoing, it will be apparent that the present invention provides a novel core drill unit particularly designed and constructed for permitting the insertion of additional pipe sections in the drilling string without moving the core bit or core barrel from the bottom of the well. The outer jacket may be telescoped downwardly over the inner spline body for a connection therebetween to cause a simultaneous rotation of the spline body and core drill with the outer jacket member. The core drill may be rotated independently of the inner core barrel to greatly facilitate the recovery and collection of the core sample therein. Furthermore, the outer housing may be raised in the well bore completely independently of the inner spline body and core barrel, thereby precluding the necessity of breaking the core sample when adding an extra pipe section to the drill string. Thus, a core sample of a substantially greater length may be recovered for an accurate analysis of the subsurface formation.

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Changes may be made in the combination and arrangement of parts asheretofore set forth-in the specification and shown in the drawings,it being understood that any modification in the precise embodiment of the invention may be made within the scope of the following claims without departing from the spirit of the invention.

I claim: v

l. A core drill apparatus for a well bore comprising an inner housing, an outer housing telescopically disposed over the inner housing, means carried by the inner housing for coring the well, spline means cooperating between the inner and outer housing members to provide for a simultaneous movement therebetween, said spline means comprising a plurality of spaced lug members provided on the outer housing, a plurality of J-shaped grooves pro vided on the inner housing and having one open end for receiving the lugs therein, said'spline means disengaged in one position to provide for longitudinal movement of the outer housing with respect to the inner housing without movement of the coring means from the bottom of the well bore, a core barrel disposed within the inner housing and extending longitudinally therethrough, means providing for rotational movement of the inner housing and coring means independent of the core barrel, means precluding a complete disengagement of the outer housing from the inner housing, and passageway means providing for; fluid circulation through the apparatus.

I 2. A core drill unit for a wellbore comprising an outer housing member telescopically disposed over "an inner housing member, male spline means provided'on the outer housing, J-sh'aped female splines having one 'open end provided on the inner housing to cooperate with the male splines in one position for locking the housing members for simultaneous movement therebetween, and in another position to permit longitudinal movement of the outer housing relative to the inner housing member, a core drill carried by the inner housing member, a core barrel disposed within the inner housing and extending longitudinally therethrough, and bearing means provided between the core barrel and the inner housing topermit free wheeling of the inner housing independent of the core barrel. 1

3. In a core drill apparatus for a well bore, comprising a cylindrical outer jacket, an inner spline body,'cooperating spline means providedon the outer jacket and inner spline body to permit telescopic movement therebetween, said spline means comprising a plurality of. spaced lug members provided on the outer housing, a plurality of spaced J-shaped grooves provided on the inner .housing and have one open end forreceiving the'lugs therein,

said spline means engaged in one position for locking ;the inner spline body with the outer jacket for simultaneousmovement therewith, said spline means engaged in a second position to permit longitudinal movement of the outer jacket relative to the inner spline body, said spline means in said second position providing fora simultaneous rotation between the outer jacket and. inner spline body, a core bit carried by the inner spline body for simultaneous movement therewith, a core barrel disposed within the inner spline body and extending longitudinally .therethrough, means provided between the core barrel and the innerspline body to permit rotation of the inner spline body relative to the core barrel, means providing for fluid circulation through the unit to the core bit, valve means provided on the core barrel to preclude the downward passage of fluid therethrough, and means for precluding a complete separation of the outer jacket and inner spline body. 1

4. In a core drill'apparatus for a well bore, an outer tubular housing'member telescopically disposed over a spline'body, a core drill carried by the spline body, a core .barrel disposed within the spline body and extending longitudinally therethrough, a plurality of circumferentlally spaced lug members provided on the inner periphery of the outer housing member, a plurality of J-slots J-slots provided with one end. open for receiving the lug members therein, means for automatically moving the lug-members into the open end of the-J- slots upon a downwardmovement of the outer housing with respect to the spline body, said means comprising a spiral shoulder provided on-the inner housing conterminous with the open end of each J-slot, a cooperating tapered shoulder provided on each of the lug members for contacting the spiral shoulders upon a downward movement of the outer housing with respect to the inner housing, said lug members in one position in the J-slot providing a locking en gagement between the outer housing member and the spline body, said lug members in another position within the J-slots providing for a simultaneous rotation between the outer housing and the spline body, means providing for rotation of the spline body and core drill relative to the core barrel,'and passageway means providing for fluid circulation through the apparatus to the core drill.

5. A core drill unit for a well bore comprising an outer jacket telescopically disposed over a spline body, a core drill carried by the spline body, a core barrel disposed within the spline body and extending longitudinally therethrough, a plurality of J-slots providedon the spline body and having onev open end, lug means provided on the inner periphery of the outer jacket for cooperation with theJ-slots oft'he spline body to permit longitudinal movement of the outer jacket with respect to the spline body, said lug means in one position within the J-slots providing for simultaneous movement between the, outer jacket and the spline body, bearing means'providing for rotation of the spline body and core drillrelative to the core barrel, and means providing for fluid circulation through the core drill unit to the core drill for'facilitating the core drill operation. f

6. A core drill unit for a well bore comprising an outer housing member telescopically. disposed over an inner housing member, J-shaped female spline means provided on the inner housing member and having one open end, lug means provided on the outer housing to' cooperate with the female splines in one position for locking the housing members for simultaneous movement therebetween, aud in another position to permit longitudinal movement of the outer housing relative to the inner housing member, a core drill carried by the inner housing member, a core barrel disposed within the inner housing and extending longitudinally therethrough, bearing means provided between the core barrel and the inner housing to permit free wheeling of the'inner housing independent of thecore barrel, passageway means extending, longitudinally through the unit for fluid circulation to the core drill, and'means for precluding a complete separation of the inner and outer housing'members. I

'7'. A core drill apparatus for a well bore comprising an inner housing, an outer housing telescopically disposed over the inner housing, means carried by the inner housing for coring the well bore, spline means cooperating between the inner and outer housing members to provide for a simultaneous movement therebetween, said spline means comprising a plurality of spaced lug members provided on the outer housing, a plurality of J-shaped grooves provided on the inner housing andhaving one open end for receiving the lugs therein, said spline means engaged in one position to provide for longitudinal movement of the outer housing with respect to the'inner housing-without movement of the coring means from the bothousing and the inner housing, passageway means providing for fluid circulation through the apparatus to the coring means, and valve means provided on the core barrel to preclude downward movement of the fluid into the core ban-e11 w 8. A core drill apparatus for a well bore, comprising an outer tubular housing member telescopically disposed over an inner tubular housing member, a core drill carried by the inner housing member, a core barrel disposed within the inner housing member, spline means cooperating between the inner and outer housing members to alternately provide for a simultaneous rotation therebetween and for a longitudinal movement of the outer housing with respect to the inner housing without movement of the core bit 011 the bottom of the Well bore, said spline means comprising a plurality of male lug members provided on the outer housing, and a plurality of J-shaped female grooves provided on the inner housing and having one open end for receiving the lugs therein,-

and means providing for circulation of fluid through the apparatus to the core drill.

References Cited in the file of this patent UNITED STATES PATENTS 1,357,564 Hughes Nov. 2, 1920 1,582,904 Conrey May 4, 1926 1,905,497 Peters Apr. 25, 1933 2,309,866 Reed Feb. 2, 1943 2,551,995 Brown May 8, 1951 2,713,473 Talbot July 19, 1955 2,776,817 Gregory et al. Jan. 8, 1957 

